In the following description, specific reference is made, purely by way of example, to the packing industry, and in particular to cigarette packing machines for producing packets of cigarettes.
Known cigarette packing machines comprise a wrapping wheel powered to rotate about a central axis and having a number of wrapping heads equally spaced about the central axis. As it rotates, the wheel feeds each head along a wrapping path through a supply station where the head receives a sheet of wrapping material and a respective product, about which the sheet of wrapping material is folded into a U; through a first folding station where the sheet of wrapping material is folded to form about the product a tubular wrapping having two opposite open ends; and through a second folding station equipped with a folding device having a pair of movable folding elements, each cooperating with the head to fold a respective open end.
On step-operated packing machines of the above type, each wrapping head is located, with respect to the wrapping wheel, in a fixed radial position with respect to the central axis of rotation of the wheel.
On continuous packing machines of the above type, each wrapping head oscillates, in use, in the neighborhood of a radial position with respect to the central axis of rotation of the wheel, so as to keep the head facing the supply station and/or a folding tool long enough to complete the relative operation.
Packing machines of the above type are relatively expensive, on account of the movable folding elements for folding the open ends of the tubular wrapping, which are fairly complicated to produce, especially in the case of a continuous packing machine.